The present invention relates to the art of producing chewing gum base and, in particular, to an improved method by which gum base may be made more efficiently at reduced energy consumption.
Chewing gums, as they are known today include a water-soluble portion which dissipates over a period of time upon chewing, and a base portion which is insoluble and inert and, thus, remains in the oral cavity throughout mastication. Flavor and sweetness are generally attributable to the water-soluble portion, while organoleptic characteristics such as texture, resiliency, film-forming capabilities, adhesivity, softness, etc. are usually attributable to the base portion. To attain desired properties in a gum product, the base is prepared with components selected for their particular organoleptic properties, their processability and for their compatibility.
As the search for new types of gum products for commercialization continues, various different base components have been sought to achieve novel attributes in the ultimate gum product. Consequently, increased demands have been placed on gum base processing in order to incorporate the newly-discovered components. Relative to very hard components, i.e., those which are resistant to local deformation whether by penetration or shear, it has been necessary to use relatively high energy methods to break down the material before mixing with other base components. Examples of such material include hard elastomer materials especially the synthetic elastomers such as polyisobutylene, styrene-butadiene copolymer, and isobutylene-isoprene copolymer. Other components which are only difficultly mixed with gum base components include but are not limited to resins such as high and low molecular weight polyvinyl acetate which produces excellent film forming properties in the resultant base and ultimate gum composition.
For example, U.S. Pat. No. 4,187,320 to Koch, et al. discloses a two-stage process for preparing chewing gum base utilizing a solid elastomer, such as butadiene-styrene copolymer, polyisobutylene and isobutylene-isoprene copolymer, wherein the solid elastomer is initially subjected to high intensity mixing under high shear conditions to obtain a substantially uniform, lump-free mass followed by the step-wise addition of an elastomer solvent to the mixer containing the masticated solid and thence the step-wise addition of an oleaginous plasticizer. High intensity mixing is conducted during the step-wise addition of both the elastomer solvent and the oleaginous plasticizer and is continued until a substantially molten, uniform mass is obtained. The second stage in the process is the step-wise addition of the remaining chewing gum base ingredients such as a hydrophobic plasticizer, a non-toxic vinyl polymer, as well as additional oleaginous plasticizer and an emulsifier. Additional optional ingredients including fillers may be added either during stage one or stage two, although, preferably, the filler is added during stage two, typically as the first stage two ingredient.
Further in this regard, U.S. Pat. No. 3,995,064 to Ehrgott, et al., describes a process for preparing a chewing gum base on a batchwise or a continuous basis which includes mixing chewing gum elastomer and solvent under high shear conditions to form a first dry solids mixture; mixing the first dry solids mixture with hydrophobic plasticizer and hydrophilic plasticizer under reduced shear conditions and increased folding action to form a second mixture; then mixing the second mixture with oleaginous plasticizer and emulsifier under rapid folding action and substantially no shear to form chewing gum base. Similarly, U.S. Pat. No. 4,329,369 to Tezuka, et al., is listed as of interest in that it shows a "one-step" method of preparing a chewing gum composition by inclusion of all necessary gum components in an intensive mixing apparatus and kneading until thoroughly mixed.
Processes such as those set forth above require, as previously explained, a high energy consuming method of preparing for/and mixing the base components. Adherence to predominantly mechanical mastication methods may well be attributable to a belief that opening up a macromolecular structure, such as that of an elastomer or resin, in any other fashion would contribute to the degradation of the very property for which it is used.
Furthermore, whether by batch method or continuous process, time is required to break the components open and for mixing them until a single relatively homogeneous gum base is attained. By the present invention, however, these problems as well as others encountered in the preparation of gum base have been to a great extent overcome.